Process for preparing acetylene in an electric arc reactor



United States Patent 3,395,194 PROCESS FOR PREPARING ACETYLENE IN ANELECTRIC ARC REACTOR David P. Keckler, Lakewood, and John EdwardLoeitler, Jr., Lyndhurst, Ohio, assignors to Diamond ShamrockCorporation, a corporation of Delaware N0 Drawing. Continuation-impartof application Ser. No. 487,594, Sept. 15, 1965. This application June6, 1966, Ser. No. 555,214

12 Claims. (Cl. 260-679) ABSTRACT OF THE DISCLOSURE In the preparationof acetylene in an electric are reactor from a hydrocarbon feed, theconversion to acetylene in the reaction zone is accomplished bymaintaining the temperature in the reaction zone within the range fromabout 1100 to 4200 C. and by maintaining the pressure therein at asuperatmospheric pressure up to about 20 atmospheres. By such operationacetylene yields are substantially equivalent to atmospheric pressureoperation, or can be enhanced, and other advantages include increasedheat recovery after downstream quenching. Also, when acetylene recoveryinvolves compression operation, relatively pure reactor inlet gases canbe subjected to compression rather than compressing contaminated, e.g.,soot and tar-containing, reaction gases.

This is a continuation-in-part of our co-pending application Ser. No.487,594, filed Sept. 15, 1965.

The present invention relates to a process for the preparation ofacetylene from a hydrocarbon material. More particularly, the presentinvention relates to a process for the preparation of acetylene from ahydrocarbon by means of electrical energy. Specifically, the presentinvention relates to a process for the preparation of acetylene from ahydrocarbon by means of an electric arc reactor.

At the present time the production of acetylene by pyrolysis-typereactions is generally carried out either by the so-called partialoxidation process or the electric arc process. The partial oxidationprocess comprises the combustion of hydrocarbons, particularly theparaffinic hydrocarbon. methane, in the presence of oxygen. Basically,the process comprises preheating the hydrocarbon and oxygen separately,mixing the heated gases in a mixing chamber, and discharging the mixedgases into a reactor where a flame is maintained and the reaction iseffected at temperatures approximatiing 1500 to 2500 C. While thereaction appears simple, the operation of the process under conditionswhich will give good yields of acetylene is diflicult.

In the partial oxidation process, the atomic constituents of hydrogen,carbon and oxygen are involved. At the reaction temperatures used inthis process, chemical equilibrium would dictate that the gaseousproducts consist almost totally of H H O, CO and CO Acetylene appearsalmost entirely as an intermediate component and, accordingly, it isnecessary to stop the reaction before completion of the chemicalequilibrium by quenching while acetylene is at a peak level. Byquenching the reaction products when the acetylene is at the peak level,acetylene decomposition is held to a minimum. However,

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despite such quenching the outlet gases from commercial reactors containsubstantially less than 10% 'by volume acetylene, the remainder beingpredominantly hydrogen, carbon monoxide, water vapor and undesiredcarbonaceous products. The economics involved in such a process areadversely influenced by low concentrations of acetylene and the presenceof undesired carbonaceous material which makes acetylene recovery andpurification more diflicult.

In the partial oxidation process, heat is quickly added to thehydrocarbon feed that is not consumed by the oxidation reactions and thepyrolysis reactions commence at a high rate to form acetylene as anintermediate product. However, acetylene decomposition reactionscommence as soon as acetylene is formed. The endothermic nature of theseoxidation and pyrolysis reactions quickly lowers the reactiontemperature and as the temperature drops, the relative rate of theacetylene decomposition reaction increases with respect to the reactionscreating acetylene. This effect, in addition to a variable combustionpattern of the flame reaction, a variable flow pattern within thereactor and the difliculty of quenching the reaction products at anoptimum time because of the flame and flow patterns, limits theconversion to acetylene that can be attained. Also, the acetylene yieldis dependent upon the amount of preheating, the oxygen to hydrocarbonratio, the reaction time and the pressure at which the reaction isoperated. At elevated pressures, i.e., in excess of atmosphericpressure, the rate of acetylene decomposition is greatly increased.

Basically, the electric arc process disclosed in the prior art comprisespassing gas which usually contains a hydrocarbon feed generally in thepresence of a diluent gas such as hydrogen, argon, etc., hereinaftercalled an arc gas, through an electric arc zone which is formed betweena pair of electrodes, i.e., cathode and anode, decomposing thehydrocarbon feed to form acetylene, hydrogen and carbon in a very shortperiod of time, generally in the order of a fraction of a millisecond.For the above atmospheric pressure conditions described more fullyhereinbelow, such time period is generally on the order of a fraction ofa millisecond or less, e.g., 0.01- 0.5 millisecond, to suppressacetylene decomposition, although longer time periods can be employed,especially where concomitant carbon production is desired. The electricarc zone is the defined area between the cathode and anode within whichthe electrical energy of the electric arc is concerned terminating orimpinging at one or more are strike points or terminus points. The arcstrike point may vary depending upon a number of fac tors which includethe reactor configuration or design (including external magneticfields), the energy input, the arc gas velocity, etc. This point,however, can be readily determined by those skilled in the art with anygiven reactor design, energy input, arc gas velocity, etc. The nature ofthe electric arc is such that the arc gas is ionized in the electric arczone creating a high temperature gaseous discharge stream of the arcgas, hereinafter usually called an ionized gas stream or plasmastreaming. In similar manner, arc reactors producing a high ion-contentplasma stream are often referred to in the art as plasma reactors.

The electric arc produces temperatures within the range from about 800C. near the surface of the electrodes to more than 5000 C. within theelectric arc zone thereby creating varying energy levels within the arczone resulting in a discontinuity which abruptly changes the energy ofthe gaseous elements within the arc zone resulting in varying degrees ofchemical conversion of the hydrocarbon feed. The gases at the lowertemperatures are only slightly ionized, whereas the gases at the hightemperatures are highly dissociated and ionized, which can result inminimal production of acetylene and the formation of relatively largequantities of carbon.

In the electric arc process only the atomic constituents, carbon andhydrogen, need be involved and the unfavorable equilibrium discussedhereinabove with a carbon-hy drogen-oxygen system is eliminated.However, with the exception of the variable flame pattern probleminvolved in the partial oxidation process, the same factors areencountered in existing electric arc processes; particularly thecompeting reactions of the decomposition of the hydrocarbon molecules toacetylene, hydrogen and carbon and the reverse action of therecombination of the decomposition products to form a hydrocarbon andcarbon. As with the partial oxidation process the net yield of acetylenefrom any arc process is critically dependent upon the effectiveness andspeed of cooling the product gas stream to temperatures well below therange of rapid decomposition. As a consequence thereof, a majorproportion of the work to date has involved extensive investigation ofvarious types of quenching methods to bring the temperature of theproduct gases below the decomposition temperatures of acetylene tofreeze the decomposition reaction at that point when the maximum amountof acetylene is present in the product gases.

It has now been found that a process for achieving maximum production ofacetylene from hydrocarbons in an electric arc reactor may be achievedby converting the hydrocarbon to acetylene with electrical energy in areaction zone by subjecting the hydrocarbon feed in the reaction zone toa temperature maintained within the range from about 1100 C. to 4200 C.,and superatmospheric pressures up to about 20 atmospheres, preferablyabout 2.5 to atmospheres, for a sufficient period of time to effectconversion of the hydrocarbon feed to acetylene. It has been found thatthe conversion of a hydrocarbon to acetylene in an electric arc reactorapproaches a product composition dependent upon the temperature andpressure employed if the hydrocarbon is brought to and maintained in thereaction zone of the electric arc reactor within the above range oftemperature and pressure. Specifically, it has been found that when ahydrocarbon feed is subjected to a plasma stream within a post are zoneof the electric arc reactor, or when a hydrocarbon plasma stream isreacted in the electric arc zone of a reactor, conversions of 80% ormore of the hydrocarbon feed to acetylene, equivalent to prior artelectric are methods employing atmospheric and sub-atmosphericpressures, are obtained by subjecting the hydrocarbon feed in thereaction zone to a temperature within the range of about 1100 to 4200C., and preferably 1100 to 2500 C. when a hydrocarbon feed is subjectedto a plasma stream within a post are zone of a reactor, with operatingpressures maintained as high as atmospheres, preferably from 2.5 to 10atmospheres. The post are zone is the defined area immediately followingthe arc strike point or terminus point of the arc zone, wherein themajor proportion of the arc gas is substantially entirely in an ionizedstate, taking into account normal strike point fluctuations arising fromgas turbulence. The reaction zone for subjecting a hydrocarbon feed to aplasma stream within a post are zone, begins at the arc strike point andterminates at the point where the product gases are quenched; thereaction zone for a hydrocarbon plasma stream reacted in the electricarc zone, begins at the contact point of feed hydrocarbon with theelectric arc and terminates at the point where the product gases arequenched.

By adjusting the energy input of the electric arc apparatus to providean average reaction temperature within the reaction zone to within theabove range, i.e., 1100 to 4200 C., and preferably 1100" to 2500 C. forsubjecting a hydrocarbon feed in a post are zone to a plasma stream,acetylene yields from the hydrocarbon feed obtained at pressures as highas 20 atmospheres are substantially equivalent or higher than acetyleneyields of prior art electric arc operations operated at atmosphericpressure or less. By being able to operate at these higher pressurescertain advantages result, for instance, smaller equipment and pipingsizes can be employed more conveniently than normally required inelectric arc operations conducted at atmospheric or subatmosphericpressures; reduction in compression requirements of the extensivecompression operation prior to acetylene recovery and purification; andpermitting increased heat recovery at the higher pressure. As the gasesproduced subsequently have to be compressed in order to separate theacetylene from the other products, operating at superatmosphericpressure also allows a savings in plant costs and power consumption ascompared to operations conducted at pressures of atmospheric or less.Also, since the product gases leaving the post-arc zone have to berapidly cooled to a temperature below about 1000 0, preferably belowabout 600 C. with a quenching medium such as water in order to avoiddecomposition of the acetylene, heat can be recovered from the quenchingmedium to supply the heat requirements of the operation therebyachieving a saving of steam. Further, by operating at superatmosphericpressures up to about 20 atmospheres, with pressure of 2.5 to 10atmospheres being especially preferred, the removal of residual soot andscrubbing of undesirable organics, e.g., naphthalene and heavyacetylenes, in the product gas stream prior to compression is aided. Inother words, operating at superatmospheric pressure simplifies theacetylene recovering and purification portion of the plant and heatrecovery.

As mentioned previously, in an electric arc the arc gas generally issubject to a wide variance in temperature levels therein and cannot beeasily regulated. However, the power input of the electric arc can beadjusted or manipulated so that, for a hydrocarbon plasma stream reactedin an electric arc zone, or for a hydrocarbon feed subjected to a plasmastream within a post are zone, the average temperature in the reactionzone can be maintained within the desired temperature range.

In the practice of the present invention the arc gas may be composed ofeither a diluent gas, i.e., hydrogen, argon, etc., as the soleconstituent, or of the hydrocarbon feed which is to be converted toacetylene. If the arc gas comprises the diluent gas as the soleconstituent, the hydrocarbon feed is introduced into the electric arcapparatus at approximately the arc strike point of the arc gas in thearc zone, and preferably just downstream from the arc strike point.Turbulence of the hydrocarbon feed, which can be assisted by fluctuationin the arc strike point, as well as normal turbulence of the arc gas,achieves a uniform mixture of the plasma stream and hydrocarbon feedmaterial forming a reaction gas in the post are zone where atemperature, preferably within the range from about 1 to 25 00 C. ismaintained at superatmospheric pressure. In the event the arc gascomprises a hydrocarbon feed as its sole constituent, the major portionof the hydrocarbon which is converted to acetylene is preferably the arcgas converted in the reaction zone where a temperature within the rangefrom about 1100 to 4200 C. is maintained at superatmospheric pressure,but a minor portion of the hydrocarbon for conversion to acetylene canbe introduced into the electric arc reactor at approximately the arcstrike point, and preferably just downstream from the arc strike point,for conversion in the post-arc zone. Usually, where no minor portion ofhydro carbon is introduced at approximately the arc strike point, gas ismaintained within the reaction zone for less than about 0.5 millisecond,and preferably for about 0.2 milli second or less to suppress carbonformation.

When virtually all of the hydrocarbon feed to be converted to acetyleneis introduced into the electric arc apparatus at approximately the arcstrike point, the arc gas preferably comprises a mixture of diluent gasand hydrocarbon feed with an especially preferred arc gas compositioncomprising mixture of hydrogen and hydrocarbon wherein the hydrocarboncontent of the arc gas comprises about 1% to 95%, preferably 3% to 15%by volume, of the total volume of the hydrocarbon feed material which isto be converted to acetylene. The remaining hydrocarbon is introducedinto the electric arc reactor at approximately the arc strike point. Byachieving a uniform mixing of the plasma stream and hydrocarbon feed inthe reaction zone a high conversion to acetylene is advantageouslyattained in less than 0.5 millisecond, preferably between about 0.1 to0.25 millisecond.

High conversions of the feed hydrocarbon to acetylene are achieved (atsuperatmospheric pressures within the above temperature range andreaction times) without the formation of free carbon exerting anyappreciable affect on the reaction composition. The equilibrium state ofthe particular hydrocarbon feed employed may be readily calculated usingwell recognized procedures of relating the heat energy input, to theamount and composition of the hydrocarbon stream. One such procedurewhich may be employed is referred to as the Free Energy MinimizationMethod, Journal of Chemical Physics, vol. 28, No. 5, 75l-755; ChemicalEngineering, Feb. 19, 1962, 121- 128. By employing this method, theenergy input, gas feed flows and compositions may be adjusted to providethe desired final gas composition.

Any electric arc reactor, including those of the socalled plasma jetdesign, i.e., a reactor producing a high ion-content plasma stream,wherein the electric arc strike point can be determined or known and onecapable of withstanding the high pressures used may be employed. Sincethe temperatures in the reaction zone should be maintained within theabove indicated ranges at superatmospheric pressures to achieve maximumconversion of the hydrocarbon feed to acetylene with minimum conversionto carbon, it is desirable to reduce the heat losses in the reactionzone by employing low heat conducting materials, for example, tungsten,carbon, etc. as construction material in this section of the electricarc apparatus.

Once equilibrium is achieved for conversion in a post arc reaction zone,or for direct conversion in an electric arc zone, the product gas shouldbe rapidly quenched to avoid decomposition of the acetylene to carbonand/or polymerization of the acetylene containing product, if thetemperature of the product gas is allowed to be slowly lowered. Suchquenching or cooling of the product gas should be effected in a matterof microseconds to a temperature below about 1000 C., preferably belowabout 600 C. Cooling to ambient temperatures may then proceed at asomewhat slower and more conventional rate. To achieve the high rate ofinitial cooling, injection of cold gas or liquid, i.e., hydrocarbon,water, etc., into the product gas is normally employed. It is, ofcourse, preferred that the gas or liquid entrained or admixed with thehot product gases, be of such a nature, that it does not contaminate theproduct stream with gases difiicult to remove. Water has been found tobean especially suitable quenching medium for use with the presentinvention.

Suitable hydrocarbon feed materials which may be employed can besaturated or unsaturated hydrocarbons and aromatics containing up to 8or more carbon atoms. Exemplary of saturated hydrocarbons includemethane, ethane, propane, isopropane, butane, isobutane, pentane, etc.;exemplary of suitable unsaturated hydrocarbons include ethylene, thepropylenes; the butylenes, etc.; exemplary of suitable aromatics includebenzene, toluene and the xylenes. The preferred hydrocarbon feedmaterials are the saturated aliphatic hydrocarbons containing 1 to 4carbon atoms with methane being the especially preferred feed material.The hydrocarbon feed, e.g., methane employed does not need to be pure;for instance, commercial sources of methane, e.g., from natural gas andoff-gases, containing small amounts of other hydrocarbons may beemployed. The concentration of acetylene based on conversion of the feedwill vary with the amount of diluent gas, preferably, hydrogen,employed. The atomic ratio of hydrogen to carbon should be maintainedapproximately within the range from about 4 to 10:1 to achieve maximumacetylene yields and prevent excess dilution that makes the recovery ofacetylene difiicult.

In order that those skilled in the art may better understand the presentinvention and the preferred method by which it may be practiced, thefollowing specific examples are offered.

Example I Into an electric arc reactor of the plasma-jet design,operated under a pressure of 4 atmospheres, is introduced 33 m. per hour(measured at 1 atmosphere and 25 C.) of hydrogen and 16.5 in. per hour(measured at 1 atmosphere and 25 C.) of natural gas. The hydrogen streamand natural gas stream are separately preheated to 600 650 C. andcombined and introduced into the reactor as the arc gas which serves tocarry the electric are between the cathode and anode of the reactor. Atapproximately the arc strike point an additional 16.5 in. per hour(measured at 1 atmosphere and 25 C.) of natural gas, preheated to 600C., is introduced into the reactor. A uniform mixture between thenatural gas stream and plasma stream is attained. The atomic ratio ofhydrogen to carbon is about 5.7 to 1. This mixture of reaction gas ismaintained in the reaction zone for approximately 0.25 millisecond andpasses through a temperature range from about 2600 C. to about 1100 C.as the gases progress to the quench point, whereby the product gasstream is rapidly quenched with water to a temperature of about C. Inaddition to the heat added to preheat the gas stream about 117 kw. perhour of electrical energy is added to the reactor. Heat loss to thereactor cooling water is equivalent to about 18 kw. per hour.

The resulting product stream is found to contain about 31.6 pounds ofacetylene (on an hourly production level), which is equivalent to anacetylene concentration in the product gas stream (dry basis) of 14.6%,by volume.

Example II Into an electric arc reactor of the plasma jet design,operated under a pressure of about 5 atmospheres, is introduced 39.5 m.per hour (measured at 1 atmosphere and 25 C.) of hydrogen and 2 in. perhour (measured at 1 atmosphere and 25 C.) of natural gas. The hydrogenstream and natural gas stream are separately preheated to about 600 C.and combined and introduced into the reactor as the arc gas which servesto carry the electric are between the cathode and anode of the reactor.At approximately the arc strike point an additional 37.5 m. per hour ofnatural gas (measured at 1 atmosphere and 25 C.), preheated to 500 C.,is introduced into the reactor. A uniform mixture between the naturalgas stream and plasma stream is attained. The atomic ratio of hydrogento carbon is about 5.7 to 1. This mixture of reaction gas is maintainedin the post-arc zone of the reactor at a temperature level within therange of about 2600" to 1100 C. for approximately 0.25 millisecond afterwhich the product gas stream is rapidly quenched with Water to atemperature of about 150 C. In addition to the heat added with thepreheated gas streams about 141 kw. per hour of electrical energy isadded to the reactor. Heat loss to the reactor cooling water isequivalent to about 21 kw. per hour.

The resultingproduct stream is found to contain about 36 pounds ofacetylene (hourly basis), which is equivalent to an acetyleneconcentration (dry basis) in the product gas of 14.1%, by volume.

Example III TABLE 1 Percent Percent Percent conversion conversionconversion Pressure (atnL) of feed to of feed to of feed to acetyleneacetylene acetylene at l,727 C. at '2,027 C. at 2,227 C.

Based on the carbon content of the hydrocarbon in the feed gases relatedto the carbon content of the acetylene 111 the product gases.

As can be readily seen from these data that by employing an elevatedreaction temperature, acetylene conversion is substantially as good orbetter at elevated pressures, i.e., 5, and atmospheres, as atatmospheric pressure.

Example IV Another series of runs are performed following the procedureof the previous examples at various temperatures and pressure levels inthe reaction zone, except that hydrogen is employed as a diluent gas andthe atomic ratio of hydrogen to carbon of the reaction gas is 7 to 1.The acetylene conversion at the various temperatures and pressures arepresented in Table 2, below.

TABLE 2 Percent Percent Percent conversion conversion conversionPressure (atm.) of feed to of feed to of feed to acetylene acetyleneacetylene at 1,727 C. at 2,027 C. at 2,227 C.

Based on the carbon content of the hydrocarbon in the feed gases relatedto the carbon content of the acetylene 1n the product gases.

These data likewise demonstrate that high conversion of acetylene isobtained at elevated pressures in an electric arc reactor by maintainingthe desired temperature range within the reaction zone.

Example V Into an electric arc reactor operated at a pressure of 4atmospheres, is introduced 245 111. per hour (measured at 1 atmosphereand C.) of natural gas. No other gas is added. The natural gas ispreheated at about 500 C. and is maintained within the reactor, frominitial exposure to the arc, to subsequent quenching for less than0.0001 second. From initial exposure to the arc until subsequentquenching, the gas is maintained within the temperature range from about4000 C. to about 1100 C. (just before quenching).

In addition to the heat added to the gas stream during preheating, about730 kw. per hour of electrical energy is added to the reactor. Heat lossto the reactor walls is equivalent to 125 kw. per hour. The resultingproduct stream is found to contain about 210 pounds of acetylene. On adry basis, the product gas contained about 23% acetylene by volume.

It is to be understood that the invention is not limited by the specificexamples and embodiments described hereinabove, but includes suchchanges and modifications as may be apparent to one skilled in the artupon reading the appended claims.

What is claimed is:

1. A method for preparing acetylene in a reaction zone of an arc reactorfrom a hydrocarbon feed which comprises the steps of establishing andmaintaining said zone at a superatrnospheric pressure maintained withinthe range from about 2.5 atmospheres up to about 20 atmospheres and atemperature maintained within the range from 4200 C. down to about 1100C., and subjecting said feed within said zone to said temperature andpressure conditions for a sufficient period of time to eifect conversionof said feed to acetylene.

2. The method of claim 1 wherein the hydrocarbon feed is a saturatedhydrocarbon containing from about 1 to 8 carbon atoms.

3. The method of claim 1 wherein the pressure in the reaction zone ismaintained within the range from 2.5 to 10 atmospheres.

4. The method of claim 1 wherein the conversion of the hydrocarbon feedto acetylene is effected in the reaction zone in less than 0.5millisecond.

5. The method of claim 1 wherein the product is rapidly quenched as itleaves the reaction zone with a quenching medium to a temperature belowabout 1.000" C.

6. A method for preparing acetylene in an electric arc reactor from ahydrocarbon feed containing 1 to 8 carbon atoms which comprises thesteps of ionizing an arc gas in an electric arc zone to form an at leastpartially ionized are gas stream, forming a reaction gas containing saidhydrocarbon feed and said are gas stream in a reaction zone of saidreactor, establishing and maintaining said zone at a superatmosphericpressure maintained within the range from about 2.5 atmospheres up toabout 20 atmospheres and a temperature maintained within the range from4200 C. down to about 1100 C., subjecting said reaction gas in saidreaction zone to said temperature and pressure conditions for asuflicient period of time to effect conversion of said hydrocarbon feedto an acetylene-containing product gas and recovering acetylene fromsaid product.

7. The method of claim 6 wherein the hydrocarbon feed is a saturatedhydrocarbon containing from about 1 to 8 carbon atoms and the arc gas isselected from the group consisting of hydrogen, a hydrocarbon containing1 to 8 carbon atoms and a mixture of hydrogen and hydrocarbon containing1 to 8 carbon atoms.

8. The method of claim 7 wherein the arc gas contains 1% to by volume,of the total volume of hydrocarbon to be converted to acetylene.

9. The method of claim 6 wherein hydrocarbon feed is introduced into thereactor at about the arc strike point.

10. The method of claim 6 wherein the pressure in the reaction zone ismaintained within the range from 2.5 to 15 atmospheres, and theconversion time of the hydrocarbon feed to acetylene is less than 0.5millisecond.

11. A method for preparing acetylene in an electric arc reactor from ahydrocarbon feed containing 1 to 8 carbon atoms which comprises thesteps of introducing said hydrocarbon feed into an electric arc zone,establishing and maintaining a reaction zone, which zone includes saidelectric arc zone, at a superatmospheric pressure maintained within therange from about 2.5 atmospheres up to about 20 atmospheres and atemperature maintained within the range from 4200 C. down to about 1100"C., subjecting gas within said reaction zone to said temperature andpressure conditions for a period of time sufficient to affect conversionof hydrocarbon feed to an acetylene-containing product gas, andquenching said product gas downstream from the electric arc zone,wherein said reaction zone begins with the introduction of thehydrocarbon feed into the electric arc zone and terminates with thequenching of product gas.

9 12. The method of claim 11 wherein the pressure in the reaction zoneis maintained within the range from 2.5 to 15 atmospheres, and theconversion time of the hydrocarbon feed to acetylene is less than about0.5 millisecond.

References Cited UNITED STATES PATENTS 2,985,698 5/ 1961 Pechtold et a1260-679 10 3,051,639 8/ 1962 Anderson 260-679 3,248,446 4/1966 Pollocket a1. 260--679 FOREIGN PATENTS 29,612 4/ 193 3' Netherlands.

DELBERT E. GANTZ, Primary Examiner.

J. D. MYERS, Assistant Examiner.

